The aim of this project is to understand the functional significance of eukaryotic genome organization. This will be accomplished by analysing in detail a length of DNA from the genome of the nematode Caenorhabditis elegans. Starting from a genetically mapped, cloned fragment, a series of overlapping fragments will be isolated from a region of the genome where many genes have already been identified by mutation. A physical map of this region will then be constructed by mapping repeated sequences and transcribed regions relative to the genes. The physical map will be compared in two strains of C. elegans and in a closely related second species to analyse mechanisms of evolutionary divergence and to identify functional sequences as those sequence arrangements which have been conserved over time. The expression of the genes in the cloned segment will be assayed during different developmental stages.